/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.apache.hadoop.util;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.apache.hadoop.classification.InterfaceAudience;
import org.apache.hadoop.classification.InterfaceStability;
import org.apache.hadoop.io.IOUtils;

import java.io.IOException;
import java.io.InputStream;
import java.util.Properties;

/**
 * This class returns build information about Hadoop components.
 */
@InterfaceAudience.Private
@InterfaceStability.Unstable
public class VersionInfo {
    private static final Log LOG = LogFactory.getLog(VersionInfo.class);

    private Properties info;

    protected VersionInfo(String component) {
        info = new Properties();
        String versionInfoFile = component + "-version-info.properties";
        InputStream is = null;
        try {
            is = Thread.currentThread().getContextClassLoader()
                .getResourceAsStream(versionInfoFile);
            if (is == null) {
                LogFactory.getLog(getClass()).warn("Could not find '" +
                        versionInfoFile + "' in Thread.currentThread().getContextClassLoader().  Trying this.getClass().getClassLoader()");
                is = this.getClass().getClassLoader().getResourceAsStream(versionInfoFile);
            }
            if (is == null) {
                throw new IOException("Resource not found");
            }
            info.load(is);
        } catch (IOException ex) {
            LogFactory.getLog(getClass()).warn("Could not read '" +
                    versionInfoFile + "', " + ex.toString(), ex);
        } finally {
            IOUtils.closeStream(is);
        }
    }

    protected String _getVersion() {
        return info.getProperty("version", "Unknown");
    }

    protected String _getRevision() {
        return info.getProperty("revision", "Unknown");
    }

    protected String _getBranch() {
        return info.getProperty("branch", "Unknown");
    }

    protected String _getDate() {
        return info.getProperty("date", "Unknown");
    }

    protected String _getUser() {
        return info.getProperty("user", "Unknown");
    }

    protected String _getUrl() {
        return info.getProperty("url", "Unknown");
    }

    protected String _getSrcChecksum() {
        return info.getProperty("srcChecksum", "Unknown");
    }

    protected String _getBuildVersion() {
        return getVersion() +
                " from " + _getRevision() +
                " by " + _getUser() +
                " source checksum " + _getSrcChecksum();
    }

    protected String _getProtocVersion() {
        return info.getProperty("protocVersion", "Unknown");
    }

    private static VersionInfo COMMON_VERSION_INFO = new VersionInfo("common");

    /**
     * Get the Hadoop version.
     * @return the Hadoop version string, eg. "0.6.3-dev"
     */
    public static String getVersion() {
        return COMMON_VERSION_INFO._getVersion();
    }

    /**
     * Get the subversion revision number for the root directory
     * @return the revision number, eg. "451451"
     */
    public static String getRevision() {
        return COMMON_VERSION_INFO._getRevision();
    }

    /**
     * Get the branch on which this originated.
     * @return The branch name, e.g. "trunk" or "branches/branch-0.20"
     */
    public static String getBranch() {
        return COMMON_VERSION_INFO._getBranch();
    }

    /**
     * The date that Hadoop was compiled.
     * @return the compilation date in unix date format
     */
    public static String getDate() {
        return COMMON_VERSION_INFO._getDate();
    }

    /**
     * The user that compiled Hadoop.
     * @return the username of the user
     */
    public static String getUser() {
        return COMMON_VERSION_INFO._getUser();
    }

    /**
     * Get the subversion URL for the root Hadoop directory.
     */
    public static String getUrl() {
        return COMMON_VERSION_INFO._getUrl();
    }

    /**
     * Get the checksum of the source files from which Hadoop was
     * built.
     **/
    public static String getSrcChecksum() {
        return COMMON_VERSION_INFO._getSrcChecksum();
    }

    /**
     * Returns the buildVersion which includes version,
     * revision, user and date.
     */
    public static String getBuildVersion() {
        return COMMON_VERSION_INFO._getBuildVersion();
    }

    /**
     * Returns the protoc version used for the build.
     */
    public static String getProtocVersion() {
        return COMMON_VERSION_INFO._getProtocVersion();
    }

    public static void main(String[] args) {
        LOG.debug("version: " + getVersion());
        System.out.println("Hadoop " + getVersion());
        System.out.println("Subversion " + getUrl() + " -r " + getRevision());
        System.out.println("Compiled by " + getUser() + " on " + getDate());
        System.out.println("Compiled with protoc " + getProtocVersion());
        System.out.println("From source with checksum " + getSrcChecksum());
        System.out.println("This command was run using " +
                ClassUtil.findContainingJar(VersionInfo.class));
    }
}
